In this application we are requesting partial funding for a state of the art single photon emission computer tomogram (SPECT) to improve the quality of the research carried out at the University of Pennsylvania. The existing instruments at Penn (rotating scintillation camera systems) are inadequate in terms of spatial resolution and sensitivity and are unable to acquire dynamic imaging which is necessary for quantitative studies of the brain. In the past few years several biologically important SPECT compounds have been introduced by our chemistry group with potential widespread applications for neuropsychiatric disorders. In contrast to flow tracers which are trapped in the brain and remain so for an extended period of time, cerebral concentration of these compounds changes considerably with time and require dynamic imaging. SPECT instruments equipped with rotating Anger camera heads are incapable of short interval dynamic imaging which can be used to generate time activity curves for quantitative modelling. We sincerely believe that with proper imaging techniques, these novel compounds have the potential of revolutionizing the investigation of neuropsychiatric diseases.